One approach to delivering healthcare in developing countries is through voucher programmes, where vouchers are distributed to a targeted population for free or subsidised health care. Using inclusion/exclusion criteria, a search of databases, key journals and websites review was conducted in October 2010. A narrative synthesis approach was taken to summarise and analyse five outcome categories: targeting, utilisation, cost efficiency, quality and health outcomes. Sub-group and sensitivity analyses were also performed. A total of 24 studies evaluating 16 health voucher programmes were identified. The findings from 64 outcome variables indicates: modest evidence that vouchers effectively target specific populations; insufficient evidence to determine whether vouchers deliver healthcare efficiently; robust evidence that vouchers increase utilisation; modest evidence that vouchers improve quality; no evidence that vouchers have an impact on health outcomes; however, this last conclusion was found to be unstable in a sensitivity analysis. The results in the areas of targeting, utilisation and quality indicate that vouchers have a positive effect on health service delivery. The subsequent link that they improve health was found to be unstable from the data analysed; another finding of a positive effect would result in robust evidence. Vouchers are still new and the number of published studies is limiting.